In the specification of our South African Patent No 92/9110 we disclose a conveyor system for transporting flowable solid material, such as grain, from a source, such as a ship's hold, to a storage silo, a warehouse or the like. A feature of the conveyor system is that, in the event of a breakdown or an emergency situation, the conveyor involved is shut down together with all those upstream of it. If the first conveyor of the series onto which the solid material is initially dumped stops then the equipment which is dumping the solid material onto that conveyor should also stop. This equipment, to ensure continuous flow of solid material onto the first conveyor rather than intermittent flow, is usually a suction unit. This comprises a suction nozzle having a bottom inlet and a discharge outlet onto the first conveyor of the series. Raising and lowering means are provided for the nozzle so that it can be lowered into the hold, immersed in the material and then lifted from the empty hold.